Compressor waste heat driven cooling system

ABSTRACT

Provided in some embodiments is a system that includes a gas compressor including an engine, a compressor driven by the engine, and a vapor absorption cycle (VAC) system driven by waste heat from the compressor, wherein the VAC system is configured to cool at least one medium. In other embodiments is provided a method that includes generating waste heat while compressing a gas, driving a vapor absorption cycle (VAC) system with the waste heat, and cooling at least one medium via the VAC system.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/929,751 entitled “Compressor Waste Heat Driven Cooling System”, filedJun. 27, 2013, now U.S. Pat. No. 8,931,291 issued Jan. 13, 2015, whichis a continuation of U.S. patent application Ser. No. 12/835,582entitled “Compressor Waste Heat Driven Cooling System”, filed Jul. 13,2010, now U.S. Pat. No. 8,474,277 issued Jul. 2, 2013 both of which areherein incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention relates to gas compressors. More particularly, thepresent invention relates to a gas compressor employing a cooling systemdriven by compressor waste heat.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Gas compressors are used in a wide variety of industries includingaerospace, automotive, oil and gas, power generation, food and beverage,pharmaceuticals, water treatment, and the like. The gas may include air,nitrogen, oxygen, natural gas, or any other type of gas. Gas compressorsgenerally include devices that increase the pressure of a gas bydecreasing (e.g., compressing) its volume. During the compression ofgas, heat energy is developed as a byproduct. Unfortunately, this heatenergy is generally expelled as wasted heat energy. Thus, the wastedheat energy represents a significant efficiency loss in the gascompressors.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a perspective view of an exemplary compressor system having avapor absorption cycle system driven by waste compressor heat inaccordance with an embodiment of the present technique;

FIG. 2 is a schematic diagram of an embodiment of a compressor systemwith a single compressor stage and a vapor absorption cycle systemdriven by waste compressor heat;

FIG. 3 is a schematic diagram of an embodiment of a compressor systemwith multiple compressor stages and a vapor absorption cycle systemdriven by waste compressor heat;

FIG. 4 is a schematic diagram of an embodiment of a compressor systemwith multiple compressor stages and multiple vapor absorption cyclesystems driven by waste compressor heat; and

FIG. 5 is a schematic diagram of an embodiment of the vapor absorptioncycle system in the compressor system of FIG. 2.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Certain embodiments discussed below include a system and method thataddresses one or more of the above-mentioned inadequacies of aconventional compressor system. In certain embodiments, a systemincludes an engine, a compressor driven by the engine, and a vaporabsorption cycle (VAC) system driven by waste heat from the compressor.In some embodiments, the compressor includes a single compression stage,while in other embodiments the compressor includes multiple compressionstages. In certain embodiments, multiple compression stages generatewaste heat to drive a single VAC system. In other embodiments withmultiple compression stages and multiple VAC systems, each compressionstage generates waste heat to drive a separate VAC system. The VACsystem is configured to cool at least one medium. For example, in someembodiments the cooled media includes components of the compressorsystem, electronics, building spaces, or fluids. Before discussingembodiments of the present technique and system, it may be beneficial todescribe a compressor system that may employ such a system.

FIG. 1 illustrates an embodiment of a compressor system 10 employing aVAC system 48 (see FIG. 2) driven by waste compressor heat in accordancewith aspects of the present technique. The compressor system 10 isgenerally configured to compress gas in various applications. Forexample, the compressor system 10 may be employed in applicationsrelating to the automotive industries, electronics industries, aerospaceindustries, oil and gas industries, power generation industries,petrochemical industries, and the like.

Generally the compressor system 10 includes one or more of areciprocating, rotary, axial, and/or a centrifugal gas compressor thatis configured to increase the pressure of (e.g., compress) incoming gas.In the illustrated embodiment, the compressor system 10 includes acentrifugal compressor. More specifically, the depicted embodimentincludes a Turbo-Air 9000 manufactured by Cameron of Houston, Tex. Insome embodiments, the compressor system 10 includes a power rating ofapproximately 150 to approximately 3,000 horsepower (HP), dischargepressures of approximately 80 to 150 pounds per square inch (PSIG) andan output capacity of approximately 600 to 15,000 cubic feet per minute(CFM). It will be appreciated that, although, the illustrated embodimentincludes only one of many compressor arrangements that can employ theVAC system 48, other embodiments of the compressor system 10 may includevarious compressor arrangements and operational parameters. Forinstance, the compressor system 10 may include a different type ofcompressor (e.g., a smaller, portable compressor), a lower horsepowerrating suitable for applications having a lower output capacity and/orlower pressure differentials, a higher horsepower rating suitable forapplications having a higher output capacity and/or higher pressuredifferentials, and so forth.

In the illustrated embodiment, the compressor system 10 includes acontrol panel 13, a drive unit 14, a compressor unit 16, an intercooler17, a lubrication system 18, and a common base 20. The common base 20generally provides for simplified assembly and installation of thecompressor system 10. For example, the control panel 13, the drive unit14, the compressor unit 16, intercooler 17, and the lubrication system18 are coupled to the common base 20. This enables installation andassembly of the compressor system 10 as modular components that arepre-assembled and/or assembled on site.

The control panel 13 typically includes various devices and controlsconfigured to monitor and regulate operation of the compressor system10. For example, in one embodiment, the control panel 13 includes aswitch to control system power, and/or numerous devices (e.g., liquidcrystal displays and/or light emitting diodes) indicative of operatingparameters of the compressor system 10. In other embodiments, thecontrol panel 13 includes advanced functionality, such as a programmablelogic controller (PLC) or the like.

The drive unit 14 generally includes a device configured to providemotive power to the compressor system 10. The drive unit 14 is employedto provide energy, typically in the form of a rotating drive unit shaft,which is used to compress the incoming gas. Generally, the rotatingdrive unit shaft is coupled to the inner workings of the compressor unit16, and rotation of the drive unit shaft is translated into rotation ofan impeller that compresses the incoming gas. In the illustratedembodiment, the drive unit 14 includes an electric motor that isconfigured to provide rotational torque to the drive unit shaft. Inother embodiments, the drive unit 14 may include other motive devices,such as a compression ignition (e.g., diesel) engine, a spark ignition(e.g., internal gas combustion) engine, a gas turbine engine, a steamturbine, a hydro turbine, a wind turbine, or the like.

The compressor unit 16 includes a gearbox 21 that is coupled to thedrive unit shaft. The gearbox 21 generally includes various mechanismsthat are employed to distribute the motive power from the drive unit 14(e.g., rotation of the drive unit shaft) to impellers of the compressorstages. For instance, in operation of the system 10, rotation of thedrive unit shaft is delivered via internal gearing to the variousimpellers of a first compressor stage 22, a second compressor stage 24,and a third compressor stage 26. In the illustrated embodiment, theinternal gearing of the gear box 21 typically includes a bull gearcoupled to a drive shaft that delivers rotational torque to theimpeller.

It will be appreciated that such a system (e.g., where a drive unit 14that is indirectly coupled to the drive shaft that delivers rotationaltorque to the impeller) is generally referred to as an indirect drivesystem. In certain embodiments, the indirect drive system may includeone or more gears (e.g., gearbox 21), a clutch, a transmission, a beltdrive (e.g., belt and pulleys), or any other indirect couplingtechnique. However, another embodiment of the compressor system 10,although not illustrated here, may include a direct drive system. In anembodiment employing the direct drive system, the gear box 21 and thedrive unit 14 are essentially integrated into the compressor unit 16 toprovide torque directly to the drive shaft. For example, in a directdrive system, a motive device (e.g., an electric motor) surrounds thedrive shaft, thereby directly (e.g., without intermediate gearing)imparting a torque on the drive shaft. Accordingly, in an embodimentemploying the direct drive system, multiple electric motors can beemployed to drive one or more drive shafts and impellers in each stageof the compressor unit 16.

In FIG. 1, the gearbox 21 includes features that provide for increasedreliability and simplified maintenance of the system 10. For example,the gearbox 21 includes an integrally cast multi-stage design forenhanced performance. In other words, the gearbox 21 includes a singecasting including all three scrolls helping to reduce the assembly andmaintenance concerns typically associated with systems 10. Further, thegearbox 21 includes a horizontally split cover for easy removal andinspection of components disposed internal to the gearbox 21.

As discussed briefly above, the compressor unit 16 generally includesone or more stages that compress the incoming gas in series. Forexample, in the illustrated embodiment, the compressor unit 16 includesthree compression stages (e.g., a three stage compressor), including thefirst stage compressor 22, the second stage compressor 24, and the thirdstage compressor 26. Each of the compressor stages 22, 24, and 26includes a centrifugal scroll that includes a housing encompassing oneor more gas impellers. In operation, incoming gas is sequentially passedinto each of the compressor stages 22, 24, and 26 before beingdischarged at an elevated pressure.

Operation of the system 10 includes drawing a gas into the first stagecompressor 22 via a compressor intake 30 and in the direction of arrow32. As illustrated, the compressor unit 16 also includes a guide vane34. The guide vane 34 includes vanes and other mechanisms to direct theflow of the gas as it enters the first compressor stage 22. For example,the guide vane 34 typically imparts a whirling motion to the intake airflow in the same direction as the impeller of the first compressor stage22, thereby helping to reduce the work input at the impeller to compressthe incoming gas.

After the gas is drawn into the system 10 via the compressor intake 30,the first stage compressor 22 compresses and discharges the compressedgas via a first duct 36. The first duct 36 routes the compressed gasinto a first stage 38 of the intercooler 17. The compressed gas expelledfrom the first compressor stage 22 is directed through the first stageintercooler 38 and is discharged from the intercooler 17 via a secondduct 40.

Generally, each stage of the intercooler 17 includes a heat exchangesystem to cool the compressed gas. An intercooler stage is typicallyprovided after each compressor stage (e.g., 22, 24, and 26) to reducethe gas temperature and/or to improve the efficiency of each subsequentcompression stage. For example, in the illustrated embodiment, thesecond duct 40 routes the compressed gas into the second compressorstage 24 and a second stage 42 of the intercooler 17 before routing thegas to the third compressor stage 26.

After the third stage compresses the gas, the compressed gas isdischarged via a compressor discharge 44 in the direction of arrow 46.In the illustrated embodiment, the compressed gas is routed from thethird stage compressor 26 to the discharge 44 without an intermediatecooling step (e.g., passing through a third intercooler stage). However,other embodiments of the compressor system 10 may include a third stageof the intercooler 17 configured to cool the compressed gas as it exitsthe third compressor stage 26. Further, additional ducts may be coupledto the discharge 44 to effectively route the compressed gas for use in adesired application (e.g., drying applications).

In the illustrated embodiment, the intercooler 17 comprises, or is partof, a vapor absorption cycle (VAC) system to cool a fluid (e.g., liquidor gas). In particular, the VAC system uses the heat energy from eachcompression stage to drive a cooling system. In one embodiment, eachintercooler 17 stage provides the waste compressor heat to a singlecommon VAC system. In another embodiment, each intercooler 17 stageprovides the waste compressor heat to an independent VAC system. Inturn, the cooling provided by the one or more VAC systems may be used tocool a variety of fluids. For example, the VAC cooling may be used forair conditioning, cooling electronics, cooling lubricants (e.g., oil),cooling water, drying air, and so forth.

FIG. 2 illustrates an embodiment of the compressor system 10 with thesingle compressor stage 22 and VAC system 48. The compressor system 10includes an engine 50, compressor unit 16, intake 30, controller 52, andVAC system 48. The engine 50 provides rotational torque to a shaft 54 torotate the shaft 54 in a rotational direction indicated by arrow 56. Theengine 50, as mentioned above, may include compression ignition (e.g.,diesel) engine, spark ignition (e.g., internal gas combustion) engine,gas turbine engine, or other type of engine. The shaft 54 is coupled tothe inner workings of the compressor unit 16. The compressor unit 16includes the single compressor stage 22 that houses one or moreimpellers. As gas enters the compressor unit 16 through intake 30, therotation of shaft 54 drives the rotation of the impeller whichcompresses the gas. The compressed gas is discharged at an elevatedpressure as output 57 for subsequent use to harness the energy of thecompressed gas.

During the compression of the gas, the temperature of the gas increasesproducing heat 58 as a byproduct. The waste heat 58 may be removed fromthe compressor via intercooler 17 or some other heat exchanger asindicated by arrow 60. This waste heat 58 is diverted to the VAC system48 as indicated by arrow 62. The VAC system 48 may use the waste heat58, as described in more detail in FIG. 5, to drive the operation of theVAC system 48 to generate a cooling output. The cooling output isdiverted to one or more media through conduits 64 with valves 66 tocontrol the flow of the cooling output through the conduits 64. The VACsystem 48, as well as the valves 66 of the conduits 64, are regulated bythe controller 52. The controller 52 may be located within the controlpanel 13 or within another location of the compression system 10. Thecontroller 52 may regulate the percentage of the cooling output to bediverted to each media based on the cooling needs of the media. Thecontroller 52 may selectively open and close the valves 66 to enableonly one flow of cooling output to a single media, or multiple flows ofcooling output to multiple media. The controller 52 also regulates theengine 50 of the compression system 10.

The cooling output of the VAC system 48 may be used to cool componentsof the compression system 10 such as the engine 50, the gas intake 30,the controller 52, or the control panel 13. The VAC system's coolingoutput may also be used to cool a building space 68, electricalequipment or electronics 70, or one or more fluids 72. The buildingspace 68 may include dedicated rooms for power distribution centers,control centers, storage, and any other function. The electricalequipment or electronics 70 may include compressor electronics, externalelectronics, robotics, automation equipment, machinery, and any otherequipment. The fluid 72 may include a liquid, gas, or a combinationthereof. Examples of liquids include water (e.g., present in theintercooler 17 or other cooling system), liquid nitrogen, gasoline,ionic liquids, lubricants (e.g., oil), coolant (e.g., liquids), and anyother liquids. Examples of gases include air, inert gases (e.g.,nitrogen or helium), natural gas (e.g., methane or propane), oxygen,carbon dioxide, ammonia, and any other gases or gas mixtures. Thecooling output may be used for other media or applications 74, such asair dryers, water chillers, and air pre-coolers, as well as, otherapplications. Thus, the cooling output maybe used solely for coolingcomponents of the compression system 10 as well as systems or spacesexternal to the compression system 10. In addition, the compressorsystem 10 may be portable and include an output (e.g., quick releaseport) to provide cooled air for any desired use; thus, the portable unitallows the user to select the cooling application.

FIG. 3 illustrates an embodiment of the compressor system 10 withmultiple compressor stages 22, 24, and 26, and the VAC system 48 drivenby waste compressor heat. The illustrated compressor system 10, similarto the embodiment in FIG. 2, includes engine 50, compressor unit 16,compressor intake 30, controller 52, and VAC system 48. The compressorunit 16 includes three compression stages, including the first stagecompressor 22, the second stage compressor 24, and the third stagecompressor 26. Although the embodiment illustrates three compressionstages, the compressor unit 16 may include any number of compressionsstages (e.g., 2 to 10 or more). Each compressor stage 22, 24, and 26houses one or more impellers. As described above, gas enters thecompressor unit 16 via the intake 30. The engine 50 drives the rotation,as indicated by arrow 56, of the shaft 54. In turn, the shaft 54 drivesthe rotation of the impellers within compressor stages 22, 24, and 26which compresses the gas. As mentioned above, the compressed gas isdischarged at an elevated pressure as output 57 for subsequent use.

During the compression of the gas at each compressor stage 22, 24, and26, waste heat 58 is generated as a byproduct, which may be removed viathe intercooler 17 or some other heat exchanger as indicated by arrows60. The intercooler 17 may include multiple intercooler stages with anintercooler stage specifically associated with each compressor stage 22,24, and 26. In certain embodiments, the first compressor stage 22generates approximately 30 to 70 percent of the waste heat 58, thesecond compressor stage 24 generates approximately 25 to 45 percent ofthe waste heat 58, and the third compressor stage 26 generatesapproximately 15 to 35 percent of the waste heat 58. This waste heat 58collected from all three compressor stages 22, 24, and 26 is diverted toVAC system 48 as indicated by arrows 62. In some embodiments, the wasteheat 58 may only be recovered from one or two of the compressor stages22, 24, and 26. In other embodiments, the compressor stage 22, 24, or26, or any combination thereof, used to supply waste heat 58 to the VACsystem 48 may be altered on a continuous basis. Such alteration mayoccur via the controller 52, which regulates both the VAC system 48 andthe engine 50, or some other mechanism. As mentioned above, the VACsystem 48 may use the waste heat 58 to drive the operation of the system48 to generate a cooling output. The cooling output is then diverted toone or more media, as described above, through conduits 64. Also, asdescribed above, the controller 52 may regulate the diversion of thecooling output to the various media.

FIG. 4 illustrates an embodiment of the compressor system 10 withmultiple compressor stages 22, 24, and 26, and multiple VAC systems 48driven by waste compressor heat 58. The illustrated compressor system10, similar to the embodiment in FIG. 3, includes engine 50, compressorunit 16, compressor intake 30, and controller 52. The compressor unit 16includes three compression stages, including the first stage compressor22, the second stage compressor 24, and the third stage compressor 26.Each compressor stage 22, 24, and 26 houses one or more impellers. Thecompressor system 10 also includes multiple VAC systems 48, including afirst VAC system 76, a second VAC system 78, and a third VAC system 80.Although the embodiment illustrates three VAC systems 48, the compressorsystem 10 may include any number of VAC systems 48, e.g., 2 to 10 ormore. As described above, gas enters the compressor unit 16 via theintake 30. The engine 50 drives the rotation, as indicated by arrow 56,of the shaft 54. In turn, the shaft 54 drives the rotation of theimpellers within compressor stages 22, 24, and 26 which compresses thegas. As mentioned above, the compressed gas is discharged at an elevatedpressure as output 57 for subsequent use.

During the compression of the gas at each compressor stage 22, 24, and26, waste heat 58 is generated as a byproduct, which may be removed viathe intercooler 17 or some other heat exchanger. As noted above, theintercooler 17 may include multiple intercooler stages with anintercooler stage specifically associated with each compressor stage 22,24, and 26. More specifically, waste heat 58 generated from the firstcompressor stage 22 is diverted to the first VAC system 76 to drive theoperation of system 76 to generate a cooling output. The cooling outputfrom the first VAC system 76 may be used to cool components of thecompression system 10. For example, the first VAC system 76 may beconnected via conduits 64, with valves 66 to control the flow of thecooling output, to the engine 50, the controller 52, the intake 30, orcontrol panel 13. More specifically, if the engine 50 is a combustionengine, the cooled engine components may include engine coolant (e.g.,water), engine lubricant (e.g., oil), engine control unit, and any otherengine component. If the engine 50 is an electric engine, then cooledengine components may include coils and any other engine component.

Also, waste heat 58 generated from the second compressor stage 24 isdiverted to the second VAC system 78 to drive operation of system 78 togenerate a cooling output. The cooling output from the second VAC system78, delivered via conduits 64, may be used to cool a building space 68or electronic equipment or electronics 70. The building space 68 mayinclude storage space, server room, power distribution room, and anyother room or space.

Further, waste heat 58 generated from the third compressor stage 26 isdiverted to the third VAC system 80 to drive operation of system 80 togenerate a cooling output. The cooling output from the third VAC system80, delivered via conduits 64, may be used to cool one or more fluids 72as described above. The fluid 72 may include a liquid, gas, or acombination thereof. Examples of liquids include water (e.g., present inthe intercooler 17 or other cooling system), liquid nitrogen, gasoline,ionic liquids, lubricants (e.g., oil), coolant (e.g., liquids), and anyother liquids. Examples of gases include air, inert gases (e.g.,nitrogen or helium), natural gas (e.g., methane or propane), oxygen,carbon dioxide, ammonia, and any other gases or gas mixtures. Thecooling output from the third VAC system 80 may also be used to coolother media or applications 74, such as air dryers, water chillers, andair pre-coolers, as well as, other applications.

As described above, the controller 52 may regulate the diversion of thecooling outputs to the various media. As illustrated, the multiple VACsystems 48 (e.g., 76, 78 and 80) provide independent supplies of coolingoutput, which may be used alone or in combination with one another tocool various spaces, fluids, machinery, electronics, and applications ina facility. Thus, the independent VAC system 48 as well as the valves 66and conduits 64 enable a wide range of cooling to be provided by thewaste heat 58. For example, the controller 52 may control the flow ofwaste heat 58 to each VAC system 48 and the cooling output from each VACsystem 48 in response to cooling demands of the various applications.Furthermore, the medium or media connected to each VAC system 48 mayvary. For example, the different VAC systems 48 may cool gases (e.g.,air or nitrogen) and liquids (e.g., oil, water, or coolant liquids),which then may be used to cool other systems. Also, in some embodiments,each compressor stage may not be associated with an individual VACsystem 48, but may be associated with multiple VAC systems 48 or no VACsystems 48. Alternatively, multiple compressor stages may be associatedwith one of the VAC systems 48, while a single compressor stage may beassociated with the other VAC systems 48.

FIG. 5 illustrates an embodiment of the compression system 10 with theVAC system 48, illustrating a detailed embodiment of the VAC system 48.The compression system 10 includes engine 50, compressor stage 22,compressor intake 30, controller 52, and VAC system 48. The engine 50drives the rotation of the shaft 54 as indicated by arrow 56. As gasenters the compressor intake 30, the one or more impellers locatedwithin compressor stage 22 are rotated by the shaft 54 to compress thegas. The compressed gas is then discharged as output 56 for further use.Waste heat 58 generated as a byproduct from compressor stage 22 may beharvested by intercooler 17 or some other heat exchanger and used by theVAC system 48. The VAC system 48 and engine may regulated by thecontroller 52 as previously described.

The VAC system 48 includes an absorber 82, a generator 84, a condenser86, and an evaporator 88. The absorber 82 includes water which acts asan absorbent. A refrigerant (e.g., ammonia) in vapor form, with a highaffinity to dissolve in water, is mixed with and dissolved in the water.Cooling water may be circulated around the absorber 82 to maintain a lowtemperature and increase the amount of refrigerant dissolved in thewater. The rich mixture of water and refrigerant is directed to a pump90, as indicated by arrow 92, to increase the pressure of the mixture.From the pump 90, the rich mixture may pass through a heat exchanger 94prior to reaching the generator 84. In the heat exchanger 94, heat froma weak mixture of refrigerant and water returning from the generator 84to the absorber 82 may be transferred to the rich mixture entering thegenerator 84. The generator 84 uses the waste heat 58 harvested from thecompressor stage 22. The waste heat 58 acts as a heat source to increasethe temperature of the mixture of refrigerant and water. At hightemperature and high pressure, the refrigerant leaves as a vapor fromthe rich mixture, as indicated by arrow 96, leaving the weak mixture ofrefrigerant and water. The remaining weak mixture, as indicated by arrow93, is transferred back to the absorber 82 to dissolve more refrigerant.On the way to the absorber 82, the weak mixture 93 may pass through aheat exchanger 94, as mentioned above, to transfer heat to the richmixture, indicated by arrow 95, entering the generator 84.

The high temperature, high pressure refrigerant vapor 96 then passes tothe condenser 86. In the condenser 86, both the temperature and thepressure of the refrigerant vapor are reduced to condense therefrigerant into a liquid state. The liquid refrigerant passes throughan expansion valve 98 forming a low pressure, low temperaturerefrigerant liquid-vapor mixture. The refrigerant liquid-vapor mixtureis directed to the evaporator 88. Upon entering the evaporator 88, thecooling output is generated. In particular, heat is transferred from asubstance to be cooled to boil the refrigerant liquid-vapor mixture at alow temperature. The boiling of the mixture results in a low-pressurerefrigerant vapor that is transferred to the absorber 82, as indicatedby arrow 100 to repeat the process again. The evaporator 88 may includea heat exchanger 102 to facilitate the transfer of heat, indicated byarrow 104, to the refrigerant and the diversion of the cooling output tothe medium or media 106 to be cooled. For example, ambient air may passthrough the heat exchanger and be cooled and then diverted to the mediumto be cooled.

The arrangement of the VAC system 48 described above may vary in otherembodiments. For example, in embodiments using ammonia as a refrigerant,a rectifier may exist between the generator 84 and the condenser 86 toeliminate any water from the ammonia. Also, while water may act as theabsorbent and ammonia as the refrigerant, in other embodiments water mayact as the refrigerant and lithium bromide as the absorbent.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A system, comprising a vapor absorption cycle (VAC) system driven by waste heat from a compressor, wherein the VAC system includes: a generator operable for receiving the waste heat from the compressor, discharging a relatively rich mixture of refrigerant/water vapor through a first passageway and discharging a relatively weak mixture of refrigerant/water vapor through a second passageway; a condenser operable for receiving the relatively rich mixture of refrigerant/water vapor from the generator and discharging a relatively rich mixture of refrigerant/water liquid; a first heat exchanger operable for receiving the relatively weak mixture of refrigerant/water vapor from the generator and discharging the relatively weak mixture of refrigerant/water vapor to an absorber; an expansion valve operable for receiving the relatively rich mixture of refrigerant/water liquid from the condenser and discharging a relatively rich liquid/vapor mixture at a lower pressure and lower temperature; an evaporator operable for receiving the relatively rich refrigerant/water in liquid/vapor form discharged from the expansion valve and discharging a relatively rich refrigerant/water vapor to the absorber such that the absorber combines the relatively rich vapor mixture received from the evaporator with the relatively weak refrigerant/water vapor mixture received from the first heat exchanger; wherein the first heat exchanger is operable for exchanging heat between the combined flow of relatively rich and relatively weak refrigerant/water mixtures discharged from the absorber and the relatively weak refrigerant/water mixture discharged from the generator; and a second heat exchanger operable for adding heat to the relatively rich refrigerant/water mixture flow in the evaporator and cooling a cooling flow directed to remove heat from at least one medium.
 2. The system of claim 1, further comprising a controller is configured to control a plurality of independent flows of the waste heat from the compressor to the VAC system.
 3. The system of claim 2, wherein the VAC system comprises a plurality of VAC systems, wherein the controller is configured to control one or more flows of the waste heat from the compressor independently to the plurality of VAC systems.
 4. The system of claim 2, wherein the controller is configured to control a plurality of cooling flows output from the VAC system.
 5. The system of claim 2, wherein the controller is configured to control one or more cooling flows output from the VAC system for cooling the compressor, a gas intake into the compressor, an engine, the controller, or any combination thereof.
 6. The system of claim 2, wherein the controller is configured to control one or more cooling flows output from the VAC system for cooling a building space.
 7. The system of claim 2, wherein the controller is configured to control one or more cooling flows output from the VAC system for cooling electronics.
 8. The system of claim 2, wherein the controller is configured to control one or more cooling flows output from the VAC system for cooling a fluid.
 9. The system of claim 1, wherein the VAC system comprises a first VAC system driven by waste heat from a first compression stage, and a second VAC system driven by waste heat from a second compression stage.
 10. The system of claim 1, further comprising a pump operable for pumping fluid though the VAC system.
 11. The system of claim 1, further comprising an intercooler in fluid communication with the compressor and the VAC.
 12. A method for using a vapor absorption cycle (VAC) system driven by waste heat from a compressor to cool a medium, the method comprising: discharging a relatively rich mixture of refrigerant/water vapor through a first passageway of a generator and discharging a relatively weak mixture of refrigerant/water through a second passageway of the generator; condensing the relatively rich mixture of refrigerant/water vapor received from the generator to a relatively rich mixture of refrigerant/water in liquid form; exchanging heat, with a first heat exchanger, between the relatively weak mixture of refrigerant/water received from the generator and a combined flow of relatively rich and relatively weak refrigerant/water mixture flows received from an absorber; expanding the relatively rich mixture of refrigerant/water in liquid form to a relatively rich refrigerant/water liquid/vapor mixture at a lower pressure and lower temperature after the condensing; evaporating the relatively rich refrigerant/water liquid/vapor mixture to a relatively rich refrigerant/water vapor and delivering relatively rich refrigerant/water vapor to the absorber, wherein the absorber combines the relatively rich refrigerant/water vapor mixture after the evaporating and the relatively weak vapor mixture received from the first heat exchanger; delivering the combined flow of the relatively rich and relatively weak refrigerant/water vapor discharged from the absorber to the first heat exchanger; wherein heat is exchanged between the combined flow of relatively rich and weak flow mixtures from the absorber and the relatively weak refrigerant/water mixture discharged from the generator; and exchanging heat, with a second heat exchanger such that heat is added to the relatively rich refrigerant/water mixture during the evaporating and heat is removed from at least one medium with a cooling flow cooled in the second heat exchanger.
 13. The method of claim 12, further comprising controlling a plurality of independent flows of the waste heat from the compressor to the VAC system.
 14. The method of claim 12, further comprising controlling a plurality of cooling flows output from the VAC system.
 15. The method of claim 12, further comprising controlling one or more cooling flows output from the VAC system for cooling the compressor, a gas intake into the compressor, an engine, the controller, or any combination thereof.
 16. The method of claim 12, further comprising controlling one or more cooling flows output from the VAC system for cooling a building space.
 17. The method of claim 12, further comprising controlling one or more cooling flows output from the VAC system for cooling electronics.
 18. The method of claim 12, wherein the VAC system is configured to vaporize a coolant from the absorbent using the waste heat from the compressor.
 19. An apparatus comprising: an engine; a compressor operably connected to the engine; an intercooler fluidly coupled to the compressor and configured to receive waste heat therefrom; a VAC system fluidly coupled to the intercooler, the VAC system including: a generator operable for discharging a relatively rich mixture of refrigerant/water vapor through a first exit port and discharging a relatively weak mixture of refrigerant/water through a second exit port; a condenser operable for receiving the relatively rich mixture of refrigerant/water vapor from the generator and discharging a relatively rich liquid mixture of refrigerant/water; a first heat exchanger operable for receiving the relatively weak mixture of refrigerant/water vapor from the generator and discharging relatively weak mixture of refrigerant/water vapor to an absorber; an expansion valve operable for receiving the relatively rich liquid mixture of refrigerant/water from the condenser and discharging a relatively rich liquid/vapor mixture of refrigerant/water at a lower pressure and lower temperature; an evaporator operable for receiving the relatively rich liquid/vapor mixture of refrigerant/water discharged from the expansion valve and discharging a relatively rich refrigerant/water vapor to the absorber, wherein the absorber combines the relatively rich refrigerant/water vapor mixture received from the evaporator and the relatively weak refrigerant/water vapor mixture received from the first heat exchanger; a pump operable for pumping refrigerant/water flow through the VAC system; wherein the first heat exchanger is operable for exchanging heat between the combined flow of relatively rich and weak refrigerant/water mixtures discharged from the absorber and the relatively weak refrigerant/water mixture discharged from the generator; and a second heat exchanger operable for adding heat to the relatively rich refrigerant/water mixture in the evaporator and removing heat from at least one medium.
 20. The apparatus of claim 19, further comprising a controller for controlling one or more cooling flows output from the VAC system for cooling the compressor, a gas intake into the compressor, the engine, the controller, electronics or any combination thereof. 